This application is a continuation-in-part of our applications Ser. Nos. 300,016 filed Sept. 8, 1981 and 305,519, filed Sept. 25, 1981, which respectively are a continuation and a continuation-in-part of our applications Ser. Nos. 58,284 now abandoned and 58,285, now abandoned both filed July 17, 1979, and which are incorporated herein by reference.
This invention relates generally to lift cranes and more particularly concerns a traveling attachment for ring supported cranes.
In response to ever-increasing user needs, self-propelled cranes have been made capable of lifting ever greater loads. While a number of factors enter into determining crane capacity, a basic limitation arises from the fact that, inevitably, the weight of the crane and its load must be transferred to the earth in some stable fashion, and, if rotation of the load is desired, the crane-earth connection must be made stable through the arc of crane rotation.
A significant increase in crane capacity was achieved by providing a self-propelled crane with the support ring and extended boom carrier disclosed and claimed in U.S. Pat. Nos. 3,485,383 and 3,878,944, assigned to the assignee of the present invention. In this design, the weight of the crane and its load is transferred to the ground through a large diameter, track-like ring. As shown in these patents, and as practiced commercially for some years, the support ring is either blocked into place by timbers fitted and wedged beneath and completely around the ring or is supported by a plurality of jacks spaced around the periphery of the ring.